[PATCH v5 01/18] block: Add PR callouts for read keys and reservation

[Bart Van Assche]

On 3/24/23 11:17, Mike Christie wrote:
> Add callouts for reading keys and reservations. This allows LIO to support
> the READ_KEYS and READ_RESERVATION commands and will allow dm-multipath
> to optimize it's error handling so it can check if it's getting an error
> because there's an existing reservation or if we need to retry different
> paths.
> 
> Note: This only initially adds the struct definitions in the kernel as I'm
> not sure if we wanted to export the interface to userspace yet. read_keys
> and read_reservation are exactly what dm-multipath and LIO need, but for a
> userspace interface we may want something like SCSI's READ_FULL_STATUS and
> NVMe's report reservation commands. Those are overkill for dm/LIO and
> READ_FULL_STATUS is sometimes broken for SCSI devices.

Reviewed-by: Bart Van Assche <bvanassche at acm.org>